Spinal Cord Morphology - S

Question 1

What and where is the cauda equina?

Answer 1

Formed by the dorsal and ventral roots (some of which come from the conus medullaris) that course through the lumbar cistern before exiting at respective levels

Question 2

What is the lumbar cistern?

Answer 2

Expansion of the subarachnoid space from the conus medullaris to the end of the dural sac at S2

Question 3

Name the spinal cord segment applied to the sensory dermatomes: shoulder, thumb (Pollicis), little finger/elbow, nipple, umbilicus, inguinal region, big toe (Hallucis), little toe, perianal region

Answer 3

C4, C6, T1, T4, T10, L1, L5, S1, S5

Question 4

Name the spinal cord segments in relation to the motor dermatomes for: biceps, brachialis, triceps, muscles of the hand, quadriceps femoris, gastrocnemius.

Answer 4

C5-6, C6-7, C6-8, C8-T1, L2-4, L5-S2

Question 5

What levels of the SC are most prone to ischemic events?

Answer 5

Upper levels of C, T, and L (all of which are the SC enlargements)

Question 6

What a supplies the inerior 2/3rds of the SC? What does it contribute to? When can it be compromised? When blocked or damaged, what sx follow?

Answer 6

Great Anterior Artery of Adamkiewicz, contributes to the anterior spinal a

Thoracolumbar fracture, surgery for an abdominal aortic aneurysm (AAA)

Paraplegia w/o sexual function, depression

Question 7

Disruption of what leads to central cord syndrome?

Answer 7

Anterior Spinal

Question 8

What a supplies most of the blood to the posterior columns?

Answer 8

Posterior spinal aa

Question 9

What is the venous drainage for the SC?

Answer 9

Internal venous plexus of Batson

Question 10

What does the gamma efferent motor pathway drive? What does a tighter spindle mean? What does being anxious do?

Answer 10

Intrinsic intrafusal fibers of the muscle spindles for proprioception and muscle tone

Increased tone and increased sensitivity to stretch (hypertonia and hyperreflexia)

Increases spindle tightness/tone and reflex briskness

Question 11

What neurons are also considered LMNs?

Answer 11

Alpha and gamma motor neurons

Question 12

What is essential for proper performance of precise muscle patterns?

Answer 12

Optimal muscle tone set by gamma motor neurons (not too much and not too little/hyper or hypotonia)

Question 13

What is the phrenic nucleus a subdivision of?

Answer 13

The MMCC

Question 14

What does the intermediolateral nucleus do?

Answer 14

Sends preganglionic symp fibers to visceral structures

Question 15

What does the sacral autonomic nucleus do?

Answer 15

Preganglionic parasymp fibers to the bowels and bladder

Question 16

What is the fasciculus proprius?

Answer 16

Has LRST embedded in it which conducts slow pain, the “beach” of the gray matter, primitive reticular formation, diffuse fibers of slow pain tract reason why lesions of these fibers are unlikely to solve clinical issues (or cause them)

Question 17

What do spinoreticular fibers do?

Answer 17

Convey slow and visceral pain sensations to the ascending reticular activating system (ARAS)

Question 18

What do the DSCT and VSCT do and where?

Answer 18

They relay unconscious, precise proprioceptive information

DSCT does it for the LE’s and VSCT does it for the UE’s

Question 19

Where does the Rubrospinal Tract originate from?

Answer 19

The Red Nucleus in the mesencephalon

Question 20

What and where is the conus medullaris? What does it contain?

Answer 20

The tapered end of the SC in the lumbar region o L-L2

Contains extending nerve rootlets that innervate the lower sacral dermatomes, bladder, and rectum